Stop mechanism for rotating elements



Nov. 22, 1949 ZINDEL, JR 2,488,792

STOP MECHANISM FOR ROIATAING ELEMENTS Filed April 16, 1948 J3 4 IN V EN TOR. v gaaf-g z/nof L, JR.

Patented Nov. 22, 1949 I ifEFICEQ 1 Thisinventi'on relates; inegeneral, `tostop mech.- a-nisms; and-,j moreparticularly, to stopfmechafnisms adapted for use with .mechanisms includ-ing Y rotating elements.;

o ston-=1otatiorr.l ofthe :mechanism at preselected terminal.positions,I between which .the mechanism is free torot'ateirr either direction.

A; further 'object of the invention is the provision cfa sucl'r-v stop:.` means. characterizedzbyj its simplicity,4 its-1y ruggedness,` and itsI easeY of operation;y

These and-otherfobj ects of thev invention fhere'- maf-ter appearingg'will be more readilyA understood byf reference-toxthe. several views of; the accompanying.,draai/ing;Y inn which Figure; l as perspective? view showing theta'pfparato strofe the.- invention f associated: :with af pair ofvariablecapacitors ofthe type commonly-used forrtuninga radio apparatus;

Figure: is: a i fragmentary'l elevational view, partly; im section; illustrating thee inventionrin one phasenf; itsaoneration; Y

Eig-ure isaiview similar to-Figure 2',- butshow- -irrgfthea apparatus-:inv another. phase offitsgopera.-

tion.;

Figure 4Lisziaz-f1agmentary 'sectional :'vieWt taken as indicatdzby linejiaf-fofl Figure L3.-;

Figline-5 isnaai/ievwsirnilar` totFigure'fi-,z but show.- ing the parts in another position; and:

Figureetiis afragmentary sectionalxviewztaken -along'linel 6"'-6 of; liguref:Av 3; andil showin-g: the mechanism in. another condition'. ot operation,

j 'ust pri-onto: fthe; condition` shown. in *Figure 31'?A Referring; nowvvitlia more particularity tex-fthe sever-al: gures.;4 of: the drawing; illustrating the erred embodiment of f the v invention, the :nut-

meral. iii. designates, generally; the cond'enserz'as semblywhich isszof. well knowniconstructiornin oludingl twoistatcrz sections I I and- I 2;..andzco1- lresponding rotor. sections Iiand I4,z respectively,

each'comprisinggaplurality of spacedfplates.- Ro:- tors vIii and nl 4f arefiinountedupon:affcommcn shaft I5: jpnrnalled in: end:l plates: I andi lil and; are 55 adapted for rotationuinto and out of meshingrelation' with the7 stator sections; the spacing of the=platesiproviding the necessary air-*gap therebetween.: A. centrally positioned plate I8.separates-fand shieldetheY condensersvfromeach other;

Shaft' I5 extends. throughl plate Il and has'a pulley 23.. attached tothe end ISV thereof. Positionedimmediately beneath pulley "2t, and sub'- stantiallyl at vright angles-te condensershaft I5, is a drive shaft 2i journalled in -Walls'22 and 23 of a; housingfmember 24. The latter is attached, as byscrews --onlyl one of Which'is shownto plateA i? lof the condenser assembly.`

Drivey shaftZI is provided with a longitudinal slotv 2t extending alongl theY axis of said shaft (Fig-ure-2),and"fwithin which' a-key 2li -is positioned. Key Z'I-iS-pivotally secured, byahollow rivet .28; to drive shaft 2 I nwhich is preferably seyceiredtothe mid-portion ofshaft ZI 1and radially lremoved.fromthe axis of shaft I5.

The keyv is positioned so that itsrcentral'portion 2s is normally parallel4 to and flush with the outer surface ofthe drive-shafta The opposite ends of the key are provided4 with. detent portions 3f! and 3|,

W-hicnprojectfbeyond the surface of the shafttowardthetop edges of a pair of stop elements, Vor lugs, 32.and 33 positioned beneath drivefshaft 2|.-

When thekey isin its normal position paralleling.the'surface' of shaft 2l as shown in Figure l2,v the projecting portions Sii-and 3l` terminate justfshort of:.engagernent with the said lugs. The lugs-may be formed in any convenient manner buti as :more-clearly illustrated in Figure fi, pref- -erably'cornprise upwardly turned portions of the base 34 of housing 24.

Wrapped around shaft 2| is a flexible driving element: 35 preferably comprising a string or cord; which has its mid-portion passing through hollmvrivet,29,v and its ends engaged :around pulleyf-Gf-andfconnected to one vend of a coil spring 36,. the! other end of which is anchored to the pulley; assat 3i. Springe@` maintains suicient tension oncord 35 toa-ssurey immediate response -ofthe-:mechanism vtov rotation cfshaft 2 I.

It is preferred tha-tthe cord'pvass through the hollow rive-t; but'iin the broader aspect of the in vention;V other methods of positioning the central portion of thef-cordmay be employed. For convenience in describing the operation of the mechanism, that part of cord whieh appears to-the leftioffrivet 2tlg in Figures Z-.and 3, is designated by the; numeral. 35d;Y whileI the remaining portion;V to the. right of the-rivet; is designated by the: numeral;` 3511. When the.; oord; is wrapped around-the: shafti andi'. in' Contact with keyy 2:1, on

3 both sides of the pivot, the tension of the cord enables it to hold the key in its normal position parallel with the shaft, as seen in Figure 2, thus permitting the shaft to be turned in either direction.

In operation of the device, it should be understood that the apparatus is designed to terminate rotation of shaft 2| after a predetermined number of revolutions, in either direction, from terminal positions lying at opposite ends of the range of rotation. More specifically, in the device, as illustrated, it is intended to limit the rotation of shaft 2l to approximately 3 turns in each direction; three turns being just sumcient to rotate pulley 20, and therefore rotors I3 and I4, through 180, that is, from one terminal position in which the rotor plates are completely meshed with the stator plates, to another terminal position in which the plates are comoletelv out of mesh.

With particular reference to Figures 1 and 2, wherein the mechanism appears in identical positions f adjustment, let it be assumed that it is desired to change the capacitance of condenser I0. Drive shaft ZI is turned manuallyknob 38 being provided for this purpose-either to the right or left, depending upon whether it is desired to increase or decrease the capacitance. If, for example, the drive shaft is rotated in a counterclockwise direction, from the position shown in Figures 1 and 2 toward the position illustrated in Figure 3, that portion of the oord designated by the numeral 35h, on the right hand side of the pulley is drawn downwardly and wrapped around that portion of shaft 2I which lies to the right of pivot 28, thereby turning pulley 2E] and shaft I in a clockwise direction to move rotors I3 and Ill out of mesh with the stators II and I2, and thus reduce the capacitance of condenser ID. At the same time cord portion 35a, lying to the left of the pivot, is drawn upwardly away from the shaft, and wrapped around the pulley.

As the mechanism approaches the terminal position, and just prior to the last half turn of shaft 2l, (the position shown in Figure 5) cord 35a moves out of Contact with the left side of key 21, thereby releasing the key for pivotal movement in a counter-clockwise direction. As illustrated in Figure 6, continued rotation of the sha-ft, for approximately one-quarter turn, brings cord portion 35h in line with extension 3i of the key and, in response to further rotation of the shaft, oord portion 35D engages extension 3l and rotates the right end of the key inwardly to its fully retracted position.

Thus key 2l is pivoted in a counter-clockwise direction to move extension 3E] outwardly to extended position and into contact with lug 32, as illustrated in Figures 3 and 4, thereby stopping further rotation of the shaft in this direction. It is understood, of course, that when the shaft reaches this position, pulley 2D has rotated shaft I5 and consequently rotors I3 and I4 of the capacitor to the terminal position wherein they are completely out of mesh with the stator.

It is readily seen that from the terminal position just described, drive shaft 2! may be rotated only in a clockwise direction and that rotation in this direction Iwill remove the last turn of cord portion 351) from contact with the right end of the key, and cord portion 35a will wind upon the shaft to the left of the hollow rivet and into Contact with the intermediate edge 29 of the key, at the point indicated in Figure 2 by the numeral 39, thereby returning the key to its normal par..

allel position, wherein extensions 30' and 3| again clear lugs 32 and 33.

Continued rotation of the drive shaft in the clockwise direction serves to unwrap cord portion 35D from the shaft and wraps portion 35a about the left side of said shaft until the last turn of cord portion 35a. moves the key into a retracted position which is the reverse of that shown in Figure 3, i. e., a position in which extension 30 is retracted and extension 3l is extended and makes contact with lug 33, to stop further rotation in that direction.

In the device as illustrated and described, it will now be understood that the two terminal positions correspond to positions of the rotor relative to the stator. In one of said terminal positions, the plates are completely out of mesh, and, in the other terminal position, the plates are completely meshed. It is evident, of course, that the selection of these terminal positions is a matter of choice, and that by varying the relative positions and dimensions of the parts of the apparatus, other terminal positions may be selected.

rIhe particular environment in which the invention has been illustrated and described is exemplary of the principles involved, and it is to be understood that the concepts of the invention are applicable to a wide variety of mechanisms in which it is desired to stop the movement of rotating elements after` a predetermined number of revolutions.

I claim:

1. Apparatus for controlling the rotation of a rotatable member, comprising, exible drive means engaged with said member and movable with said member during rotation of the latter, a stationary stop element, and stop means on said member movable with respect to said member between a position in which said stop means engages said stop element and a position in which said stop element and said stop means are disengaged, said flexible drive means being in bearing engagement with said stop means and effective to cause movement of the latter between its said positions in response to predetermined angular displacements of said rotatable member.

2. Apparatus for controlling the rotation of a rotatable shaft, comprising, flexible drive means wrapped about said shaft in driven engagement therewith, a stop element, and stop means pivotally mounted on Said shaft for movements with respect to the shaft between a position in which said stop means engages said stop element and a position in which said stop element and said stop 4means' are disengaged, the Wrapped portion of said flexible drive means further being in bearing engagement with said stop means and being movable along the shaft, in response to predetermined angular displacements of said shaft, to cause pivotal movement of said stop means between its said positions.

3. Apparatus for controlling the rotation of a rotatable shaft, comprising, a rotary element having its axis of rotation extending transversely with respect to and spaced from the axis of said shaft, a flexible drive cord or the like having its ends secured to said rotary element and an intermediate portion wrapped about said shaft, stop structure, and detent means carried by said shaft and having spaced portions, said detent means being movable between a position in which one of said spaced portions engages said stop struc- Vture and a position in which the other of said portions is so engaged, the wrapped portion of said drive cord further being adapted for driving enshaft, a flexible drive cord or the like having its ends secured to said rotary element and an in-l termediate portion wrapped about said shaft, said shaft being provided with a slot extending longitudinally thereof, stop structure, elongated key means disposed within said slot, and means pivotally mounting said key means intermediate its ends, said key means being displaceable about said mounting means to cause selective engagement of the opposite end portions of said key means with said stop structure, the Wrapped portion of said drive cord further being in bearing engagement with said key means and being movable along the shaft in response to rotation of the latter. such movement along the shaft being effective to cause pivotal movements of said key means between its said positions.

5. Control apparatus for a variable capacitor having a control shaft, a pulley secured to said shaft, a counter-shaft radially removed from said control shaft, a drive cord interconnecting said counter-shaft with said pulley, whereby rotation of said counter-shaft turns said pulley to rotate said control shaft, a stationary element, an elongated member pivotally mounted on said counter-shaft and movable by said cord into an extended position in which said member abuts said stationary element.

GEORGE ZINDEL, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,830,595 De Tar Nov. 3, 1931 1,939,933 Wacker et al Dec. 19, 1933 

